The present invention is a unique positioning system that may be used with many processes that require precision X, Y, ⊖ movement, i.e. stage travels, in the range of up to X 1,000 millimeters, Y 5000 millimeters and ⊖45 degrees The utility of the present invention, is particularly relevant to, for example, large format substrate process tools. In another example, one may also use the positioning system in connection with printing as well as other precision production processes such as laser scribing, glue dispensing, biotechnology assaying, machining and testing. Whether one is using the positioning system for printing on large format glass substrates, assembling flat panel displays, semiconductor or other precision production process, the need for precise X, Y, ⊖ movement of the positioning system substrate is most critical, in particular where one process tool continues the work done by another tool and alignment of incoming substrate with respect to the tools is critical. For example, one tool may scribe solar panel lines and the other tool may then scribe another set of lines parallel and in close proximity to the first set of lines which are already existing on the panel. Or in another example, one tool may places small droplets of disease DNA samples on a Biochip substrate, another tool may place drug targets on top of the DNA samples and yet another tool senses the chemical reaction between the samples.
The precise movement needed during the fabrication process is made even more challenging because of the sheer size of the large substrates and the large staging required to move them. One example may be seen with tenth generation panels (3,000 by 3,000 millimeters), used for flat panel displays, which can require stage travels up to 4,000 millimeters, while typical moving chucks can weigh up to 500 kilograms. The mass and inertia of such positioning systems are a challenge for the devices that control and drive the stage. For the most stringent processes, the motion of the panel must be controlled with sub micron translational error in X, Y, Z direction. Minimizing rotational errors (pitch, yaw and roll) is particularly critical, as small rotations can result in large translations in the X, Y, and/or Z planes located at the edge of the panel. One component of the flat panel display process machines that may provide precise smoothness, flat and straight, movement is the air bearing stage. Air bearings are generally used because they allow precise, repeatable motion. However straightness and flatness of motion errors of more than 10 microns and 2 arc seconds can be expected with air bearings in large travel of 4,000 mm. Although these motion errors initially seem negligible, they generally are not acceptable for certain flat panel processes.
As mentioned above, the positioning system of the present invention may also be used with printing, scribing and inspection of large format glass substrates. Generally, the positioning system of the present invention is used to process large format glass substrates that require the use of mechanical systems, which may include a multitude of subassemblies. One such positioning system configuration may include: precision granite base with one or more air bearing slides moving on the base in X, Y, ⊖ direction, precision granite bridge beams with integrated risers mounted to the base where tools are mounted to, and steel weldment for connecting the granite base to the floor with vibration isolation mounts. Other lower cost positioning system configurations may include: a flat steel or aluminum base with recirculating bearing slide moving on the base in X, Y, ⊖ directions, aluminum or steel beam mounted on risers to the base, and steel weldment for mounting the base to the floor with or without isolation mounts. In either configuration, typically non-contact linear motors and non-contact optical encoders are needed to provide precise, repeatable X-Y motion. It will be appreciated by those skilled in the art that these two types of positioning systems with air bearings or recirculating bearings are just two of many mechanical system components that may be used for printing, inspecting or positioning of large format glass substrates. Whether one uses one of the mechanical systems similar to those just discussed or another type of mechanical system, there remains the need to position the large format glass substrates and correct for any errors associated with such positioning in X, Y, ⊖ direction. One may correct the error associated with the movement of large format glass substrates with a variety of different methods. For example, error can be corrected by external sensing devices such as cameras or laser interferometers. They can also be corrected by mapping the errors. The present invention allows for correcting the errors in the X, Y and ⊖ directions including position, straightness and yaw of large flat panels using mapping, as well as using cameras to correct for large substrate misalignment. In particular, the invention addresses the need of making large integrated X, Y and ⊖ Rotational motion for positioning large substrates in process machines, including large corrections in X, Y, ⊖ for the initial substrate or glass alignment, as well as providing an integrated mechanism for making small corrections of straightness and yaw during process motion.
Flat panel display manufacturing, printing, scribing and inspection on large format glass substrates, semiconductor fabrication and numerous other manufacturing processes all have one thing in common, they require precision motion control for feature generation and inspection. There is a present need for a positioning system, for large substrates, that may allow for long Y displacement to be simultaneously corrected during process motion, for both accuracy in the Y direction, correction of straightness errors in the X direction, and ⊖ rotational errors of yaw in the XY plane. In addition, there is a need for a positioning system that will have the kinematic flexibility for producing the required ⊖ alignment of large panel substrates as well as the requirement to generate large X and Y displacement of the stages.
It should be noted that in the foregoing description and elsewhere herein Y designates the longitudinal axis of motion of the substrate in absolute coordinate system, fixed to the machine base. X designates the transverse axis of motion of the substrate in absolute coordinate system perpendicular to Y and fixed to the machine base. θ represents a rotational axis of motion of the substrate in the XY plane. The moving coordinates, which are fixed to the substrate are designated as X′, Y′. The substrate motion can be expressed in either X′Y′ coordinate system or XY coordinate system using trigonometric transformation equations as shown in the Appendix It should further be noted, as shown in the Appendix mathematical formulation of the invention, which are an integral part of the invention, that there are forward kinematic equations and inverse kinematic transformations. The forward kinematic transform moving X1, X2, Y machine controlled axes to angle θ of the substrate and an X, Y position of any point on the Substrate in the machine fixed coordinate system.
Similarly in the inverse Kinematic equations, as shown in the Appendix, the position of X1, X2, Y axes of the mechanism are determined to position a known point Q on the substrate at a known point P on the machine with a desired angular orientation of the substrate. These trigonometric transformations, relate to dimensions and motion from the moving X′Y′ coordinate system to the fixed XY coordinate system and vice versa. In the following description references will be made to either coordinate system
It should further be noted that the following terms will be used in the foregoing discussions:
Linear Rail—a long linear bearing which is fixed to a base or a moving slide
Puck—a small slide that has a degree of freedom moving along its rail
Motorized Rail—One or two parallel Linear rails each having one or two pucks, where the rails are attached to a fixed base and the pucks are attached to a moving slide and the motion between the slide and the base is achieved by an actuator such as linear motor or a ball screw.
Positioning Stage—A device, including, motorized rails with feedback devices such as linear or rotary encoders, sometimes referred to as Positioning Table.
Positioning System—A positioning device that includes of one or more positioning stages mounted in a certain configuration, such as compounded, split axes or Gantry, and controlled by motion controller with servo amplifiers.
Positioning System Components—Components that make up the positioning system including for example rails, motors, actuators, slides, bases, encoders, cables, controllers, amplifiers and vibration isolation mounts Compounded Positioning System—A positioning system where the positioning stages are mounted one on top of the other
Integrated Positioning System—A positioning System where the same components are used to generate motion in more than one direction. Integrated positioning systems are typically of lower cost, more compact, more accurate and more robust yet their assembly must be precisely controlled.
Virtual center of rotation—A point about which the slide of the machine rotates which is not a fixed point on the slide.
Revolute joint—A rotary bearing connecting the slides of two positioning stages.